Various kinds of regenerative medicine have been developed for the purpose of the functional recovery of damaged tissues and the like. Especially, many technologies for primate, particularly human totipotent or pluripotent stem cells, of which the ultimate goal have been the regeneration of tissues per se, and the like, have been reported. Unlike embryonic stem cells, induced pluripotent stem cells (iPS cells) particularly have had an advantage that the induced pluripotent stem cells are less ethically problematic because the induced pluripotent stem cells are induced from somatic cells.
In a case of culturing primate totipotent or pluripotent stem cells (both cells are generically simply referred to as “pluripotent stem cell” in the invention), it is required to maintain the primate totipotent or pluripotent stem cells in an undifferentiated state for a long term. In order to culture the pluripotent stem cells in an undifferentiated state for a long term, feeder cells such as mouse fibroblasts are generally used.
However, it has been pointed out that the use of the feeder cells derived from heterologous animals, such as the mouse fibroblasts, cause contamination of culture liquids with foreign substances such as antigenic substances derived from heterologous animals. In a case in which totipotent or pluripotent stem cells are used in medical applications or applications equivalent thereto, it has been demanded that the cells are cultured in the absence of the feeder cells.
In view of such circumstances, cell-adhesive materials of which the functions substitute for those of feeder cells have been developed. For example, it is disclosed in Nature Biotechnology, 2001, Vol. 19, pp. 971-974 that human embryonic stem cells maintained in an undifferentiated state are successfully cultured using, as a substitute for feeder cells, Matrigel, which is a component extracted from mouse sarcoma.
In Japanese Patent Application Laid-Open (JP-A) No. 2001-17183, a cellular composition that does not contain any feeder cells but contains proliferating primate progenitor cells is disclosed, and the cellular composition that further contains an extracellular matrix is disclosed as a preferred embodiment. In Japanese Patent Application Laid-Open (JP-A) No. 2010-29186, a cell culture matrix in which a cell culture surface subjected to plasma polymerization is further coated with a coating solution containing a predetermined concentration of extracellular matrix protein and an aqueous solvent is disclosed, and it is described that the cell culture matrix has favorable adhesiveness helpful for avoiding the differentiation of embryonic stem cells. In Japanese National-Phase Publication (JP-A) No. 2012-502664, a peptide that binds to a glycosaminoglycan (GAG) is disclosed.
In Biomaterials, 2010, November; Vol. 31 (32), pp. 8281-8288 and Nature Biotechnology, 2010, Vol. 28, No. 6, pp. 606-610, recombinant or synthetic peptides containing a vitronectin partial sequence that can contribute to the long-term culture of embryonic stem cells, specifically, each of the sequence of 1st to the 52nd amino acids of natural vitronectin (see Biomaterials, 2010, November; Vol. 31(32), pp. 8281-8288) and the sequence of the 41st to 52nd amino acids containing an RGD sequence (Nature Biotechnology, 2010, Vol. 28, No. 6, pp. 606-610) are disclosed, The peptides have been known to be excellent in view of the fact that: the possibility of contamination with antigenic substances and the like can be avoided since the peptides are non-biological samples; and the peptides can be industrially produced.